The Ghueri are Epiphyte's vigilante justice force: a combination of sheriff's posse, neighborhood watch, and lynch mob. They protect most of the citizens from street crime. That doesn't include the aristocracy, who can hire their own security force. Likewise, they don't enforce their views of morality in the bars, the opium dens and the bordellos. They focus on protecting homes, businesses, and people on the streets from robbery and assault.
Organized crime on Annyrion is centered in Annyrion City. Traditionally these criminals have viewed Epiphyte as a place to vacation, or to “lay low” while the heat is on them. It was also a source of drugs that they could smuggle out to Inaria and other places where they are considered contraband (unlike in Epiphyte itself). As long as they didn't commit crimes in Epiphyte, nobody cared overly much about what they might have done elsewhere.
I posit that the fighting began when the organized crime bosses tried to set up shop in Epiphyte. All it would take is for some of these goons to go around trying to shake down the local merchants for protection money….. Next morning, the goons are found hanging from lamp-posts, and the battle is on. The aristocracy would probably not get directly involved: as long as the mobsters bribe them sufficiently, they'll look the other way. At the same time, the aristocrats are too canny to overtly ally themselves with outsiders.
About piracy in Epiphyte: 7th Wave was just setting up a HQ in Epiphyte when the blockade was placed. They weren't already established there, so you can't really say AC was acting in response to 7th Wave. Although, there may have ICly been other pirates already there before…. It's attractive to pirates for the same reason it attracted mobsters: as long as they didn't commit crimes in Epiphyte, they were welcome and could move about freely.
After the AC places a blockade, everything changes. The aristocrats, the Ghueri *and* the Kemetic priesthood all see the blockade as a threat to their way of life, and join forces. 7th Wave endears itself to them all by running the blockade. The mobsters . . . I dunno, probably lay low and wait for it all to blow over, unless somebody has a better suggestion for them.